I did something similar here but it's 15' high - needs a tractor with loader carrying round bales on a spike to get in without knocking the end trusses.. and a JCB with a high back hoe had to go in this year which was tight at that..
I also had an extension into the field behind to make a shelter and handling pens which was great but that area was uphill so the level of the leanto roof truss was only 12' and also the angle of it was too shallow a rise and collapsed after 9 years with last winter's snow

Insurance wouldn't cover it because of the "design fault" of the necessary roof angle

so it's still roofless but back to operational as a handling pen as the outer gates are fine.. and finally the tractor can get in to dig it out as 12' wasn't enough.
I reckon I would have been better off with a steel constructed one at £8k from a reputable company to be honest..